[clang] [driver] return immediately in `addArchSpecificRPath` and `getArchSpecificLibPaths` on AIX (PR #134520)

[Daniel Chen via cfe-commits]

DanielCChen wrote:

> Change LGTM, but this really ought to have a test (or affect some existing test somehow)

Agreed. Will add a test.

https://github.com/llvm/llvm-project/pull/134520